If you have own old reel to reel tapes, then it’s useful to know how long they’re going to run for. Unfortunately it’s not that straight forward to find out. There are several different speeds that tapes might have been recorded at, and even the diameter of the tape reel isn’t much of a clue. For example there could be anything between 1200 and 2400 feet of tape on a 7 inch reel (this is achieved by the tape itself varying in thickness – 2400 feet on a 7inch reel is pretty thin and much more prone to damage) ,plus of course there are all the different recording speeds to consider as well. The table below gives you a guide as to what tape running times to expect – unfortunately the only way to find out for sure is to play the tape, unless some considerate person had the foresight to label it up!

Reel to Reel Tape Running Times Per Side

Reel Size

Tape Length in Feet

1 7/8 IPS *

3 3/4 IPS *

7 1/2 IPS *

15 IPS *

-

150

16mins

8mins

04mins

2mins

-

200

22mins

11mins

5.4mins

2.7mins

-

225

24mins

12mins

6mins

3mins

-

300

32mins

16mins

8mins

4mins

-

450

48mins

24mins

12mins

6mins

5″

600

1hr 04mins

32mins

16mins

8mins

-

900

1hr 36mins

48mins

24mins

12mins

7″

1200

2hr 08mins

1hr 04mins

32mins

16mins

7″

1800

3hr 12mins

1hr 36mins

48mins

24mins

7″ or 10 1/2″

2400

4hr 16mins

2hr 08mins

1hr 04mins

32mins

10 1/2″

3600

6hr 24mins

3hr 12mins

1hr 36mins

48mins

* IPS=Inches per second – Running Times per Side

CDR

74 minutes

80 minutes

100 minutes

Not sure I would recommend 100 min discs. Not all drives support them and data is very compressed on the disc which can’t be good for accuracy.